Radiological Identification of Injury to the Kaplan Fibers of the Iliotibial Band in Association With Anterior Cruciate Ligament Injury.

BACKGROUND: Recent biomechanical studies have demonstrated that the Kaplan fibers (KFs) of the iliotibial band play a role in the control of anterolateral rotation of the knee. However, controversy exists regarding whether the KFs are injured in conjunction with anterior cruciate ligament (ACL) injury. PURPOSE: To establish the prevalence of radiological injury to the KFs in the ACL-injured knee; to evaluate the effect of the time interval between injury and magnetic resonance imaging (MRI) on diagnosis of KF injury; and to assess for any association between KF injury and other qualitative radiological findings. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Preoperative MRI scans were reviewed for 161 patients with ACL injury. Specific diagnostic criteria were developed and applied to identify KF injury. Chi-square testing was performed to look for associations among KF injury, the time from injury to MRI, and associated radiological knee injuries. RESULTS: Radiological evidence of KF injury was identified in 30 (18.6%) patients. The diagnosis of KF injury was higher in patients who had MRI scans performed within 90 days of injury as compared with ≥90 days after injury (23.7 vs 6.4%; P = .010). Patients with an MRI diagnosis of KF injury had significantly higher rates of lateral meniscal injury (40% vs 18%; P = .007), posteromedial tibial bone marrow edema (73% vs 44%; P = .003), and injury to the lateral collateral ligament (13% vs 3%; P = .019) or medial collateral ligament (23% vs 8%; P = .019). CONCLUSION: The prevalence of injury to the KF in patients with ACL injury as diagnosed by MRI was relatively low (18.6% of patients). However, the time interval from injury to MRI was relevant to diagnosis, with significantly higher rates of injury identification in patients with early (within 90 days) versus delayed (≥90 days) MRI. KF injury was associated with higher rates of injury to the lateral meniscal and collateral ligaments, as well as posteromedial tibial bone bruising.